Stability Of Mixed Blueberry(Vaccinium Corymbosum L.)and Blue Honeysuckle Berry(Lonicera Caerulea L.)during Freeze Drying And Storage And Product Development

In this paper,the stability of the mixed blueberry-blue honeysuckleberry during freeze drying and storage were studied.New products with high anthocyanins conents were further developed.The main conclusions were as follows:(1)Among the four varieties of berries,the highest contents of vitamin C(24.86 mg/100 g),calcium(28.32 mg/100 g),magnesium(15.84 mg/100 g),ash(0.54 g/100 g),protein(1.27 g/100 g)and crude fiber(1.69 g/100 g)were determined in blue honeysuckle berry through physicochemical determination and principal component analysis.In addition,blue honeysuckle berry also had the hightest content of amino acids(985.10 mg/100 g),with 16 kinds of amino acids and 7 kinds of essential amino acids.Therefore,blue honeysuckle was used as the main material formixed berry powder processing.(2)The 5:3 mix ratio of blueberry and blue honeysuckle berry pulp had the best sensory qualities in terms of E-nose,E-tongue and sensory evaluation.The immobilized water content would remain stable during the final stage of freeze drying via LF-NMR.The moisture sorption isotherm and state diagram of berry pulp can be useful in the evaluation of stability of freeze drying.The monolayer moisture content was 0.18 g H₂O/g dry solids for 5:3 berry powder.The glass transition temperature of freeze-dried berry powder was tested by the differential scanning calorimetry.The state diagram yielded the conditions of maximally-freeze-concentration at 0.361 g water/g sample,with the characteristics temperature of end point of freezing(T'_m)was-31.44? and the characteristics temperature of glass transition(T'_g)was-69.83?.(3)The storage stability of mixed blueberry-blue honeysuckle powder was evaluated at different storage temperatures(4?,25?,37?)and relative humidity(43%,75%,95%RH).The results showed that compared with other storage conditions,the basic physical and chemical indexes were better under25? 43%RH(T_g decreased at least of 4.62?)and 4? 75%RH(moisture increased at least of 4.2%)conditions for 12 weeks.In terms of antioxidant substances and activities,the retention ratios of total phenols and total flavonoids were higher(53%and 40%),and the antioxidant capacity was stronger.In terms of behavioral characteristics,flowability was maintained well.In terms of anthocyanins,the degradation of single and total conents of the six anthocyanins were the least under 25?43%RH(total degradation decreased by 23.92%,72.56 mg/g),and the total retention ratio of the six anthocyanins was higher at 4?75%RH(45.29%).The results showed that 4? 75%RH and 25? 43%RH were favorable for powder storage.(4)New product with high anthocyanin content was developed by blueberry,blue honeysuckle berry,mulberry,black chokeberry,and raspberry.According to the electronic nose,electronic tongue and artificial sensory evaluation,the optimal mixture ratio of blueberry:blue honeysuckle berry:mulberry:black chokeberry:raspberry was 5:3:2:1:1.In terms of behavioral characteristics,the flow function(ffc)value of the optimal mixed berry powder with good flowability was greater than 4.The flow energy per unit(11.75 m J/g)was not significantly different from that of other berry powders,but the compaction percentage of blueberry powder and mulberry powder was reduced by compaction,which was beneficial to processing and transportation.According to the state diagram,the critical water content of the optimal mixed berry powder for stable storage at 25? should be less than 0.90 g/100 g.Under this situation,7kinds of anthocyanins in mixed berry powder were found,in which delphinin-3-O-arabinoside presented the highest content among seven anthocyanins(166.47 mg/g).